Monowheel vehicles of various sorts exist. An advantage of a monowheel vehicle over multi-wheeled vehicles is that the radius of the wheel is maximized relative to the size of a given vehicle, enabling the vehicle to negotiate larger obstacles than conventional vehicles situated atop smaller wheels. Many of the known monowheel vehicles transport a person, where the person circumscribed by the wheel provides the propulsion power as well as balances the vehicle. An excellent catalog of the history of this seemingly bizarre type of vehicle can be found at the following web addresses: dself.dsl.pipex.com/MUSEUM/TRANSPORT/MOTORWHL/motorwhl.htm; and dself.dsl.pipex.com/MUSEUM/TRANSPORT/MOTORWHL/motorwh12.htm#coat.
A brief chronology of monowheel vehicles is presented below, primarily obtained from the websites identified above.
1869—First monowheel patent, by Bergner, featuring hand crank and foot treadle actuation (Bergner, U.S. Pat. No. 91,510). Teaches dual tires attached to a single wheel.
1869—Greene & Dyer hand crank-driven monowheel patent (Greene et al., U.S. Pat. No. 91,535)
1884—Figure from book, “Victorian Inventions” suggests a monowheel vehicle that appears to indicate dual tires attached to a single wheel like the Bergner patent.
1892—Harper pedal-powered monowheel patent (Harper, U.S. Pat. No. 511,139)
1897—Venable monowheel patent, essentially a bicycle inside a large wheel (Venable, U.S. Pat. No. 611,534). There is a suggestion to design the wheel as the outer race of a giant ball bearing with the frame comprising the inner bearing race.
1904—The Monocycle Garavaglia, the first monowheel with an engine.
1912—Coates propeller-driven monowheel patent (Coates, U.S. Pat. No. 1,046,267)
1917—D'Harlingue propeller-driven monowheel patent (D'Harlingue, U.S. Pat. No. 1,228,100)
1923—Cislaghi monowheel. Cislaghi & Govetosa received a French patent in 1924 (No. 573,801). The patent seems to indicate that the plane of the wheel can be tilted from the plane of the rider, ostensibly to keep the wheel away from the riders head. A photo from around the same time doesn't seem to show such a tilt, but a photo caption suggests retracting stabilizer wheels that extend when the vehicle stops. Cislaghi received a British patent in 1927 (No. 275647). The Motoruota company was founded by Cislaghi in 1927 in an attempt to commercialize this monowheel vehicle.
1923—E. J. Christie monowheel appears in “Everyday Science & Radio News” and features a flywheel on each side of the main, driven wheel that “act as gyroscopic balancers and rudders”.
1926—Gyrocycle pedal-powered monowheel
1932—J. H. Purves' “Dynosphere”. It is a monowheel that is wide enough that static stability provides balance from side-to-side. One photo from Popular Science depicts a smaller version that is electrically-powered.
1933—Gutierrez's 3-wheeled, “monowheel”-like armed and amphibious tank patent (Gutierrez, U.S. Pat. No. 1,915,886).
1937—Rose monowheel patent (Rose, U.S. Pat. No. 2,107,766) includes external wheel to prevent rotation due to excessive acceleration or deceleration.
1940s—Inverted pendulum control problem.
1968—Malick unicycle patent using a gyroscope to measure pitch attitude and provide feedback for control of a planar unicycle.
1994—David Vos designed and implemented a unicycle robot with automatic balance control (Vos, MIT Ph.D. thesis, May 1992).
1997—Chiba University unicycle robot employing gyroscopic actuation to provide dynamic stability about the roll axis.
2000—Owen “di-wheel” with two wheels separated by approximately one wheel diameter to permit two riders to sit in between the wheels.
2003—Jake Lyall introduces the RIOT (Re-Invention Of The) wheel. Instead of using the rider's weight to provide the reaction to the engine's thrust on the wheel, the reaction torque is provided by a lead-weighted scooter engine suspended from the main wheel axle, powered through a sprocket. The rider sits in front of the wheel and a 450-pound internal counterweight keeps the rider hovering above the ground at the front. The rider steers the vehicle by a combination of precessing a 65-pound gyroscope and shifting his weight.
2005—Wheelsurf markets a commercial monowheel vehicle. See following web address: wheelsurft.nl/.
In the monowheel examples, the human driver, circumscribed by the wheel, controls the balance and turns by leaning. The vehicle must have some velocity in order for the driver to maintain balance, using the gyroscopic effect of the spinning wheel to maintain balance, similar to a standard bicycle or motorcycle.
The present inventor realized that a monowheel vehicle that does not transport a rider has some important uses, even though complexity is somewhat increased in order to incorporate an automatic balance control mechanism. For example, a riderless vehicle could be equipped with a camera or other payload and be remotely operated at much higher speeds and over rugged terrain including climbing stairs. A monowheel vehicle presents a minimal frontal cross section, which is useful to navigate narrow entry ways, improve its ability to hide behind objects, and reduce its profile as seen from a distance. If the vehicle were able to turn at zero forward velocity, the vehicle would be able to more easily navigate confined spaces and at slower speeds. Such capability is not possible with the known monowheel vehicles.